This invention relates to tufting machines and more particularly to a method and apparatus for selectively forming cut pile and loop pile having substantially the same pile height as the cut pile in the same row of stitching in a backing material.
In Jolley, et al., U.S. Pat. No. 4,134,347 and Inman, U.S. Pat. No. 4,185,569, a method and apparatus for forming cut pile and loop pile are substantially the same pile height in the same row of stitching is disclosed. These patents represent improvement over Card, U.S. Pat. No. 3,084,645 wherein the cut pile projects substantially further from the backing than the loop pile and thus the pile height differs substantially. In McCutchen, U.S. Pat. Nos. 2,879,728 and 2,879,729, prior attempts to provide level cut and loop pile were made without success. The inventions in the aforesaid Jolley, et al., and Inman patents have been and remain very successful. This is especially true of variations of the sliding gate structure of the second embodiment illustrated in FIGS. 7-11 in the Inman patent wherein the gate slides and cooperates with the bill of the hook to open or close passage of a seized loop from the bill to the blade selectively. Those loops released from the bill remain uncut of those loops which pass to the closed end of the hook are cut.
One of the problems with the sliding gate structure which does not occur with a pivoted gate as in Jolley, et al., and the first embodiment in Inman wherein the gate pivots on the hook is that since there is lateral movement, vertical support must be provided to the gate driving mechanism. In the second embodiment of Inman and variations of this in the prior art, there must be an extension connected to the sliding gate or to the equivalent such as a sliding cut/loop clip. In Inman, which for practical reasons was not reduced to practice, this comprised a slide block supported on a fixed member of the tufting machine but in apparatus constructed in the prior art, this comprised of an extension member between the gate and the driving air cylinders which move with the hook bar as the hook rocks or oscillates. These extension members had to be supported on a member fastened to and movable with the hook backing bar and the cylinder support.
The additional linkages between the gate or clip and the air cylinder results in lost motion inefficiencies and wear problems. Moreover, the extra weight associated with the linkage, its supports, and the air cylinders moving with the hooks obviously creates undesirable momentum and inertia forces. Another problem with the prior art structure is that assembly of each separate cylinder to its link and to the gate is time consuming. This also results in additional maintenance costs due to replacement of cylinders or gates that fail or break during normal operation.